Various demands with regard to a necessary spring stiffness of spring elements are made in the loaded and unloaded condition with the application of resilient elements, i.e. with the mounting of structures in vehicle construction or rail vehicle construction. The stiffness is ideally dependent on the loading condition of the vehicle. Spring elements with a progressive spring characteristic are capable of solving this problem.
Spring elements with a progressive spring characteristic can be realised in many ways. Combinations of several helical springs, leaf springs and gas compression springs for example belong to the existing possibilities. Flexible springs, with which lever ratios change due to a deformation of the flexible springs display a corresponding behaviour. The mentioned spring elements however are characterised by a comparatively high complexity. Environmental influences such as humidity and dirt can lead to a disadvantageously high wear of such spring elements.